The present invention relates to a semiconductor technology, and more particularly, to a method for forming a micro-pattern in a semiconductor device in which a micro hole pattern having dimensions smaller than the allowed resolution is formed.
The semiconductor industry is growing at a rapid rate as semiconductor devices are becoming highly integrated and efficient. Such a rapid growth in turn has increased the demand for large-scale integration and efficiency of semiconductor devices.
Fabricating semiconductor devices includes repeatedly performing deposition process, ion implantation process, photo process, etching process, and cleaning process to form desired circuit patterns on a semiconductor substrate and certain material layers. Thus, large-scale integration and efficiency may be achieved when a sufficient level of technology for each of the processes is provided.
The etching process is one of the essential process technologies needed when forming a submicron circuit pattern having a relatively satisfactory etch profile.
Recently, double patterning technology has been introduced to form a submicron pattern with dimensions smaller than the allowed resolution.
The double patterning technology includes performing a photolithography process to form a pattern twice the size of a desired pitch and performing another round of photolithography process to further form patterns among the existing pattern, thereby forming the patterns with the desired pitch.
However, the critical dimension (CD) uniformity is determined by the overlay accuracy among masks used during the photolithography processes because the photolithography processes are performed twice.
Thus, self-aligned double patterning technology has been introduced to overcome the above-discussed limitation of the double patterning technology.
The self-aligned double patterning technology includes patterning a hard mask layer to form a hard mask pattern twice the size of a desired pitch, forming spacers over sidewalls of the hard mask pattern, removing the hard mask pattern, and etching lower layers using the spacers as masks to form a pattern of the desired pitch.
The self-aligned double patterning technology may be able to increase the CD uniformity because the process involved uses the photolithography process once. However, the current level of technology allows the self-aligned double patterning technology to be applied mostly to line patterns and generally not to hole patterns.